package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.*;

import static com.hmdp.utils.RedisConstants.QUEUE_NAME;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;
    @Resource
    private RedisIdWorker redisIdWorker;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    // 获取消息队列
    private class VoucherOrderHandler implements Runnable {
        public void run() {
            while (true) {
                try {
                    // 获取消息队列中的订单信息 XREADGROUP
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(QUEUE_NAME, ReadOffset.lastConsumed())
                    );

                    // 判断获取的消息的有效性
                    if (list == null || list.isEmpty()) {
                        //   1、如果无，说明没有消息，继续下一个循环
                        continue;
                    }
                    //   2、如果有，可以下单
                    MapRecord<String, Object, Object> mapRecord = list.get(0);
                    Map<Object, Object> value = mapRecord.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    // 创建订单
                    handleVoucherOrder(voucherOrder);
                    // ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(QUEUE_NAME, "g1", mapRecord.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    handlePendingList();
                }

            }
        }
    }
    /*阻塞队列
        private  BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024*1024);

        private class VoucherOrderHandler implements Runnable {
            public void run() {
                while (true) {
                    try {
                        // 获取队列中的订单信息
                        VoucherOrder voucherOrder = orderTasks.take();

                        // 创建订单
                        handleVoucherOrder(voucherOrder);
                    } catch (Exception e) {
                        log.error("处理订单异常", e);
                    }

                }
            }
        }*/

    private void handlePendingList() {
        while (true) {
            try {
                // 获取pending list中的订单信息 XREADGROUP
                List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                        Consumer.from("g1", "c1"),
                        StreamReadOptions.empty().count(1),
                        StreamOffset.create(QUEUE_NAME, ReadOffset.from("0"))
                );

                // 判断获取的消息的有效性
                if (list == null || list.isEmpty()) {
                    //   1、如果无，说明没有消息，继续下一个循环
                    break;
                }
                //   2、如果有，可以下单
                MapRecord<String, Object, Object> mapRecord = list.get(0);
                Map<Object, Object> value = mapRecord.getValue();
                VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                // 创建订单
                handleVoucherOrder(voucherOrder);
                // ACK确认
                stringRedisTemplate.opsForStream().acknowledge(QUEUE_NAME, "g1", mapRecord.getId());
            } catch (Exception e) {
                log.error("处理 pending list 异常", e);
                try {
                    Thread.sleep(20);
                } catch (InterruptedException ex) {
                    throw new RuntimeException(ex);
                }
            }
        }

    }

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        // 创建锁对象
        Long userId = voucherOrder.getUserId();
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        // 获取锁
        boolean isLock = lock.tryLock();
        if (!isLock) {
            log.error("不允许重复下单");
            return ;
        }
        try{
            // 获取代理对象
            proxy.createVoucherOrder(voucherOrder);
        }finally {
            lock.unlock();
        }



    }

    IVoucherOrderService proxy;
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 执行lua脚本
        // 获取用户
        Long userId = UserHolder.getUser().getId();
        // 获取订单id
        long orderId = redisIdWorker.nextId("order");
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(), String.valueOf(orderId)
        );
        assert result != null;
        int r = result.intValue();
        // 判别结果 0， 1， 2
        if (r!=0){
            // 根据返回结果，不为0则是无购买资格
            return Result.fail(r == 1? "库存不足":"不能重复下单");
        }
        // 获取代理对象
        proxy= (IVoucherOrderService) AopContext.currentProxy();
        return Result.ok(orderId);
    }


    /*@Override
    public Result seckillVoucher(Long voucherId) {
        // 执行lua脚本
        Long userId = UserHolder.getUser().getId();
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
        );
        int r = result.intValue();
        // 判别结果 0， 1， 2
        if (r!=0){
            // 根据返回结果，不为0则是无购买资格
            return Result.fail(r == 1? "库存不足":"不能重复下单");
        }
        // 为零 把下单信息保存到阻塞队列中
        long orderId = redisIdWorker.nextId("order");
        // 生成订单
        VoucherOrder voucherOrder = new VoucherOrder();
        // 订单
        voucherOrder.setId(orderId);
        // 券
        voucherOrder.setVoucherId(voucherId);
        // 用户
        voucherOrder.setUserId(userId);
        // 创建阻塞队列
        orderTasks.add(voucherOrder);
        // 获取代理对象
        proxy= (IVoucherOrderService) AopContext.currentProxy();
        return Result.ok(orderId);
    }*/
    /*  // 优化前的代码
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 查询券的信息
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        //判断 1、时间是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            // 未开始
            return Result.fail("活动尚未开始");
        }
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            // 已结束
            return Result.fail("活动已结束");
        }
        //判断 2、库存是否充足
        if(voucher.getStock() < 1){
            return Result.fail("库存不足");
        }
        Long userId = UserHolder.getUser().getId();


        // 创建锁对象
//        SimpleRedisLock lock = new SimpleRedisLock("order" + userId, stringRedisTemplate);
        // 创建锁对象,使用redisson创建锁
        RLock lock = redissonClient.getLock("lock:order" + userId);
        // 获取锁
        boolean isLock = lock.tryLock();
        // 获取代理对象（事务）
        if (!isLock) {
            return Result.fail("购买失败,不能重复下单");
        }
        try {
            IVoucherOrderService currentProxy = (IVoucherOrderService) AopContext.currentProxy();
            return currentProxy.createVoucherOrder(voucherId, userId);
        } catch (IllegalStateException e) {
            throw new RuntimeException(e);
        } finally {
            lock.unlock();
        }

    }*/


    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        // 一人一单判断
        Long userId = voucherOrder.getUserId();
        // 1、查询订单
        Long voucherId = voucherOrder.getVoucherId();
        int count = query()
                .eq("user_id", userId)
                .eq("voucher_id", voucherId)
                .count();
        // 2、判断是否存在
        if (count > 0) {
            //用户买过
            log.error("重复购买");
            return ;
        }
        // 扣减库存,  采用乐观锁
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")// set stock = stock - 1
                .eq("voucher_id", voucherId)    //where id = ? and stock > 0
                .gt("stock", 0)
                .update();
        if (!success){
            log.error("库存不足");
            return ;
        }
        // 写入数据库
        save(voucherOrder);
    }
}
